body {
  background: #cfefff; /* 仿游戏蓝天背景 */
  display: flex;
  flex-direction: column;
  align-items: center;
  padding-top: 20px;
}
/* 顶部信息栏 */
.top-bar {
  display: flex;
}
canvas {
    border: 2px solid #333;
    background-color: #fff;
}